Vibrating plate for sound instrument

ABSTRACT

A vibrating plate for a sound instrument, such as a diaphragm of a loudspeaker, a sounding board of a piano or guitar, which comprises a plate of light material, such as paper, plastics, foamed plastics, metal or the like, said plate having pipes or cells formed therein or fixed thereto, said pipes or cells being filled with fluid under high pressure, thereby increasing flexural rigidity of said vibrating plate without appreciable increasing its weight.

United States Patent Matsuura et al. 1 June 13, 1972 [54] VIBRATINGPLATE FOR SOUND 3,111,187 11/1963 Barlow ..181/D1G. 1 INSTRUMENT3,153,463 10/1964 Novak ....181/32 R 3,456,755 7/1969 Walker ....l8l/32R [721 lnvenwrsl Bldg Ma'suula; Kflmhiko m 3,477,330 11/1969 Bert....84/193 'F Ymmheko 0f Hamaklm-Shh 3,478,634 11/1969 l-laerich..84/193 Sh1zuoka-ken, Japan [73] Assignee: Nippon Gakki Seizo KabushikiKaisha, FOREIGN PATENTS OR APPLICATIONS l-lamamatsu-shi, Shizuoka-ken,Japan 513,289 10/1939 Great Britain ..181/32 R [22] led: 1971 PrimaryExaminerStephen J. Tomsky [21] App1.No.: 113,344 Attorney-Henry T.Burke, Robert Scobey, Robert S. Dunham, P. E. Henninger, Lester W.Clark, Gerald W. Griffin, Thomas P. Moran, R. Bradlee Boa], ChristopherC. Dunham [30] Foreign Application Priority Data and John F. scuny Feb.13, 1970 Japan ..45/11987 [57] ABSTRACT [52] US. Cl. ..181/32 R, 84/193511 1m. 01 ....Gl0k 13/00, H04r 7/00, G106 3/06 igzgg gfgf gz f f g zg i'xg 'g [58] Field ofSearch ..181/32 R, DIG. 1; 84/193 P g P 8 comprisesa plate of light material, such as paper, plastics, foamed plastics,metal or the like, said plate having pipes or [56] References Citedcells formed therein or fixed thereto, said pipes or cells being UNITEDSTATES PATENTS filled with fluid under high pressure, thereby increasingflexural rigidity of said vibrating plate without appreciableincreasl,828,513 lO/l93l Smythe ..181/32 R ing its weight 1,931,88510/1933 DAmour.. ...181/32 A 1,970,837 8/1934 Bowley ..181/32 A 6Claims, 11 Drawing Figures PATENTEUJUH 13 m2 3.669.214

sum 1 or a I INVENTORS 19/050 MATS'UURA A 75019 M1464 W4 VOSH/H/ MURASEATTORNEY PATENTEDJuu 13 m2 sum 3 0F 3 FIG. 7

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S mw v MUAA 0 R M540 MM mw M m 5. f w @w M I I I w m fizz/52 w m l a wATTORNEY VIBRA'I'ING PLATE FOR SOUND INSTRUMENT BACKGROUND OF THEINVENTION This invention relates to a vibrating plate for soundinstrument, such as a diaphragm of loudspeaker, a sounding board ofpiano or guitar or the like.

It is generally required for the vibrating plate for sound instrument tohave relatively light weight and relatively high flexural rigidity.Accordingly the vibrating plate has been usually made by a plate oflight material which is provided with reinforcing portions such as ribsto increase its flexural rigidity. However the provision of suchreinforcing portions necessarily increases apparent weight per area ofthe vibrating plate and therefore it is difficult to provide a vibratingplate with very light weight with high flexural rigidity.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an ideal vibrating plate which has relatively light weighttogether with relatively high flexural rigidity.

In accordance with the present invention there is provided a vibratingplate for sound instrument which comprises a plate of light materialsuch as paper, plastics, foamed plastics, metal or the like, having atleast one void in the form of pipe or cell, said void being filled withfluid under high pressure to increase flexural rigidity of saidvibrating plate.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate preferredembodiments of the present invention in which:

FIG. 1 is a rear view of a vibrating plate according to an embodiment ofthe invention;

FIG. 2 is a sectional view of the vibrating plate as shown in FIG. 1;

FIG. 3 is a front view, partly broken, of a vibrating plate according toanother embodiment of the invention;

FIG. 4 is a sectional view of the vibrating plate as shown in FIG. 3;

FIGS. 5 and 6 are front views, partly broken, showing other embodiments;and

FIGS. 7, 8, 9, l and 1 l are sectional views showing further embodimentsof the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explainedwith reference to the drawings which illustrate several embodiments ofthe invention.

FIGS. 1 and 2 illustrate an embodiment in which a vibrating plateconsists of a plate 1, a spiral fine pipe 2 fixed on the rear side ofsaid plate 1 and a radial fine pipe 3 fixed to the rear side of saidspiral pipe, said pipes 2 and 3 being filled with fluid under highpressure. The plate 1 is made of material which is usually used for thevibrating plate for sound instrument, for example, paper, plastics,foamed plastics, metal or the like, and the pipes 2 and 3 are made ofsuch material that is impermeable to the fluid used and is ratherflexible but becomes self-supporting (flexurally rigid) by the pressureof the fluid filling the pipes, for example thermoplastic resin,thermosetting resin, glass or the like. The fluid filling the pipes maybe gas such as air, hydrogen, helium, freon or carbon dioxide gas, or itmay be liquid such as water, alcohol or ketone.

The flexural rigidity of the vibrating plate as shown in FIGS. 1 and 2is considerably increased by the pressure of the fluid filling the pipes2 and 3, but the weight thereof is only a little increased by the fluidunder pressure, so that the apparent weight per area of the vibratingplate is kept at low value and thus the vibrating plate having lightweight together with high flexural rigidity is obtained. When gas isused as the fluid, it is necessary to compress relatively large quantityof gas into the pipes to high density to obtain high pressure, but whenliquid is used it is difiicult to use finer pipes filled with smallerquantity of liquid to obtain the desired increase of flexural rigiditybecause the liquid has higher bulk modulus than that of the gas.

FIGS. 3 and 4 illustrate another embodiment in which a vibrating plateconsists of a plate 11, a plurality of parallel pipes 12 fixed on onesurface of said plate and a plurality of parallel pipes 13 fixed on theother surface of said plate at right angle to the pipes 12. The plate 11and the pipes 12 and 13 may be made of some material as used in theembodiment shown in FIGS. 1 and 2, and the pipes are filled with fluidunder high pressure.

In the embodiments as shown in FIGS. 1-4, the pipes 2, 3, l2 and 13 maybe used independently or jointly. These pipes may be arranged in asingle layer and communicated together, or they may be arranged in twolayers (as shown in the drawings) or in more than two layers. The pipesmay be arranged between two plates so as to form a sandwichconstruction. It is not always necessary to make the pipe of uniformdiameter throughout its length, for example, the spiral pipe 2 as shownin FIG. 1 may be of gradually varying diameter from the center to outerend thereof. If the vibrating plate has a plurality of independentpipes, the fluid pressure may be changed in the respective pipes.

FIG. 5 illustrates another embodiment in which a plate 21 includes anetwork of pipe 22 in itself, and said pipe is filled with fluid underpressure. The network of pipe 22 may be built in the plate 21, or it maybe previously molded as a separate member, which is embedded in theplate 22.

FIG. 6 illustrates a further embodiment of the invention, in which aplate 31 has a plurality of separate cellular voids 32 therein, insteadof the network of pipe as shown in FIG. 5. The voids 32 may be formed byfoaming the material of the plate 31 at the time of molding thereof.Such cellular construction may be adopted in the other forms of thevibrating plate. For example, the spiral pipe as shown in FIG. 1 or thestraight pipes as shown in FIG. 3 may be provided with a plurality ofpartitions therein to form the cellular construction. In the cellularconstruction in which a plurality of voids are independent from eachother, if a particular part of the vibrating plate is subjected tostress, the increase of the fluid pressure owing to the stress islimited to said particular part and is not unified throughout the plate,so that any part of the plate holds sufficiently high flexural rigidity.

FIGS. 7-11 illustrate other embodiments of the present invention. FIG. 7illustrates a vibrating plate comprising a pair of sheets 41 and 42 ofplastic film, metal foil or the like which are partly bonded together toform voids 43 therebetween. The voids 43 may be arranged in the form ofa plurality of unidirectionally extending pipes, or in the form ofindependent cells.

FIG. 8 shows a vibrating plate comprising a pair of sheets 51, 52 ofplastic film, metal foil or the like and a corrugated sheet 53 ofsimilar material which is arranged between the sheets and bonded theretoto form voids 54. The voids 54 may be either formed in the form of pipesor cells. The constructions as shown in FIGS. 7 and 8 may be formed bypartly bonding the sheets together such as by ultrasonic fusion,highfrequency fusion, electric heat fusion or adhesion, and then inflating non-bonded portions by blowing fluid thereinto, or they may beformed by previously forming the sheets in predetermined shape andconnecting them together.

FIG. 9 illustrates a vibrating plate made of a plate 61 of foamedplastic such as foamed polystyrene in which are embedded pipes 62, whichare filled with fluid under high pressure. The pipes 62 may beconstructed in any form, such as radial form, spiral form or series ofparallel pipes, and it may be arranged in a single layer or a pluralityof layers. For a diaphragm of a loudspeaker, the proper flexuralrigidity can be obtained by arranging the pipe 62 in the radial formincluding radially extending trunks and many branches diverging fromsaid trunks, that is, in the form of a feather of an insect.

FIG. illustrates a vibrating plate formed by a plurality of pipes 71which are connected together being adhered side by side and filled withfluid under high pressure. FIG. 11 illustrates a vibrating plate 81having a large void 82 in the central part thereof, which is filled withfluid under high pressure. The inside surfaces of the void are connectedby means of rods 83.

In the various embodiments of the present invention as shown in thedrawings, the void in the form of pipe or cell may be charged with thefluid under high pressure at the time of forming the vibrating plate.Alternatively, the void may be connected to a pump to pressurize thevoid as desired. If the wall of the void permits slight leakage of thefluid, the void may be maintained at a predetermined pressure byutilizing phenomenon of equilibrium between gas and liquid. The platemay be reinforced by embedding prestressed glass or metal fiberstherein.

It will be understood that in accordance with the present invention theflexural rigidity of the vibrating plate can be considerably increasedwithout appreciably increasing the weight, and thus a vibrating platehaving light weight with high flexural rigidity can be obtained.

We claim:

1. A vibrating plate for a sound instrument, comprising a plate havingat least one void which is filled with fluid under high pressure toincrease flexural rigidity of said plate.

2. A vibrating plate for a sound instrument, comprising a plate and atleast one pipe fixed to said plate, said pipe being filled with fluidunder pressure to increase flexural rigidity of said plate.

3. A vibrating plate for a sound instrument, comprising a plurality ofplates partly bonded together to form at least one void therebetween,said void being filled with fluid under pressure to increase flexuralrigidity of said vibrating plate.

4. A vibrating plate for a sound instrument, comprising a plate havingat least one void in the form of pipe therein, said void being filledwith fluid under pressure to increase flexural rigidity of said plate.

5. A vibrating plate for a sound instrument, comprising a plate havingvoids in the form of cells, said voids being filled with fluid underpressure to increase flexural rigidity of said plate.

6. A vibrating plate for a sound instrument, comprising a plurality ofpipes which are connected together side by side to form a plate, saidpipes being filled with fluid under pressure to increase flexuralrigidity of said plate.

F i I i

1. A vibrating plate for a sound instrument, comprising a plate havingat least one void which is filled with fluid under high pressure toincrease flexural rigidity of said plate.
 2. A vibrating plate for asound instrument, comprising a plate and at least one pipe fixed to saidplate, said pipe being filled with fluid under pressure to increaseflexural rigidity of said plate.
 3. A vibrating plate for a soundinstrument, comprising a plurality of plates partly bonded together toform at least one void therebetween, said void being filled with fluidunder pressure to increase flexural rigidity of said vibrating plate. 4.A vibrating plate for a sound instrument, comprising a plate having atleast one void in the form of pipe therein, said void being filled withfluid under pressure to increase flexural rigidity of said plate.
 5. Avibrating plate for a sound instrument, comprising a plate having voidsin the form of cells, said voids being filled with fluid under pressureto increase flexural rigidity of said plate.
 6. A vibrating plate for asound instrument, comprising a plurality of pipes which are connectedtogether side by side to form a plate, said pipes being filled withfluid under pressure to increase flexural rigidity of said plate.